How does the typical mains power connect in the USA anyway?

I dunno.
I'm glad that this discussion hasn't turned into an insult hurling
contest as so often happens.
I think Danny now has a much better idea of how his electrical panel
works, and it's really just that part that matters. If he uses the
technically incorrect but easy to understand notion that power is
delivered by the L1 and L2 power cables that distribute power throughout
his house on red and black wires, and returns back to the panel on the
white wires, and that the L1 and L2 power sources are each 120 VAC
relative to the neutral, but 180 degrees out of phase so that there's
240 VAC between them, then he knows more than most homeowners and enough
not to electrocude himself, and that's what counts.
And, so far as I'm concerned, I'm going to drop this thread in favour of
doing something more productive with my time.
I'm going to see if I can open my mouth so wide that my head turns
inside out. I'm just wondering if I can do it. It may take some time
to find out for sure if I can do it or not.

Look on the manufacturers name plate...you'll likely see that it is
single phase.
L1 to L2 is 240 volt single phase. The center / neutral tap is not
needed for 240 volt service.
The 2 phase claim is bogus.
Beware of trolls.

The IEEE is made up of trolls? From an IEEE published paper given
at a recent IEEE conference on power engineering. You couldn't ask
for a more credible source:
http://ieeexplore.ieee.org/xpl/articleDetails.jsp?reload=true&arnumber4520128
"Distribution engineers have treated the standard "singlephase" distributio
n transformer connection as single phase because from the primary side of t
he transformer these connections are single phase and in the case of standa
rd rural distribution single phase line to ground. However, with the advent
of detailed circuit modeling we are beginning to see distribution modeling
and analysis being accomplished past the transformer to the secondary. Whi
ch now brings into focus the reality that standard 120/240 secondary system
s are not single phase line to ground systems, instead they are three wire
systems with two phases and one ground wires. Further, the standard 120/240
secondary is different from the two phase primary system in that the secon
dary phases are separated by 180 degrees instead of three phases separated
by 120 degrees."
Or how about some electrical eqpt manufacturers:
http://www.behlman.com/applications/AC%20basics.pdf
http://www.samlexamerica.com/support/documents/WhitePaper-120240VACSingleSp
litPhaseandMultiWireBranchCircuits.pdf

Neither will the IEEE power engineers:
http://ieeexplore.ieee.org/xpl/articleDetails.jsp?reload=true&arnumber4520128
"Distribution engineers have treated the standard "singlephase" distributio
n transformer connection as single phase because from the primary side of t
he transformer these connections are single phase and in the case of standa
rd rural distribution single phase line to ground. However, with the advent
of detailed circuit modeling we are beginning to see distribution modeling
and analysis being accomplished past the transformer to the secondary. Whi
ch now brings into focus the reality that standard 120/240 secondary system
s are not single phase line to ground systems, instead they are three wire
systems with two phases and one ground wires. Further, the standard 120/240
secondary is different from the two phase primary system in that the secon
dary phases are separated by 180 degrees instead of three phases separated
by 120 degrees."

Are the IEEE trolls too? You just hurl insults but refuse to address
the above that clearly shows the IEEE power engineers agree with me.
BTW, still waiting for you to give your definition of "phase".
If you know so much, why can't you do that?

Not obvious what the author has in mind in the minimal summary of his paper.
He clearly says the standard way of looking at split-phase, 3-wire
supplies is they are single phase. Everyone here but you (that has
provided an opinion) agrees with that.
The author suggests a departure where the 2 hot wires are considered
separate phases for "modeling". And for modeling, if you are looking at
the *currents* in the 3 wires, you have to consider them separate phases
because the currents will be 180 degrees out of phase only if the loads
are resistive. Not obvious what the author is saying beyond that.
But, alas, I don't see where the author's suggestion has been accepted.
The paper confirms what the rest of us have been saying.
My service panel is "single phase". If I replaced it, the only panels
manufacturers have are "single phase". The 2-pole breakers for them are
"single phase".
I propose we resolve this by using L1, in my L1-N-L2 service, as the
reference. L1-N and L1-L2 are in phase.
The standard real 2-phase supplies have 2 transformers 90 degrees apart
with the centertaps connected. Does this then have 4 phases?
In a 3-phase wye system are there 6 phases at the transformers (each
transformer has 2 ends)?

It's clear to me:
"Which now brings into focus the reality that standard 120/240 secondary sy
stems are not single phase line to ground systems, instead they are three w
ire systems with two phases and one ground wires. Further, the standard 120
/240 secondary is different from the two phase primary system in that the s
econdary phases are separated by 180 degrees instead of three phases separa
ted by 120 degrees. "
He's saying that in fact you have two phases and that's how
you have to analyze it.

He didn't say that at all.
Everyone here but you (that has

He did not say it's just for modeling.
And for modeling, if you are looking at

So, how can you consider them separate phases if they are
really not separate phases?

How about these white papers from electrical eqpt manufactuers that
clearly talk about two phases being present:
http://www.behlman.com/applications/AC%20basics.pdf
http://www.samlexamerica.com/support/documents/WhitePaper-120240VACSingleSp
litPhaseandMultiWireBranchCircuits.pdf
Are they wrong too?

No because the logical reference point to look at phases
is from the neutral common point. You have 3 phases, differing by 120 degr
ees.
Similarly, the logical reference point in a split-phase service is
the neutral common point. From that perspective, you have two phases
present. Since you brought up 3 phase, what about the other thread
I started where I used 3 phase to show how you can get to split-phase
and how it looks like two phases? A lot of people looked at that post, but
no one wants to comment? Here it is again:
Let's start with a 3 phase wye power source. For anyone
not familiar, here's a diagram of it, it's fairly straightforward:
http://central-energy.com/AppNotes.html
It's the first diagram that shows a 3 phase wye power source.
Let's assign Phase A as the reference point and make it 0 deg.
Phase B is 120 deg off from Phase A. Phase C is 240 deg off from
Phase A. You can see those 3 waveforms on a 3 input scope,
one input attached to each phase, the scope reference point tied
to the neutral. I believe everyone here is in 100% agreement that you
have 3 phases present there. Let's put that power source inside a box
and I run those 4 wires out of the box, I have 3 phases.
For convenience, let's assign each of the 3 voltage sources in
the box to be 120V. So, we have 3 phases emerging from the box,
with 120V between any phase and neutral. All this I hope we
agree is still 3 phase.
OK, so now, lets just leave everything as it is, but only run
Phase A and B and the neutral out of the box. How many phases
do I have now? I would hope that you would agree that I have
two phases, Phase A at 0 deg, Phase B at 120 deg. Again, I can
see exactly that on a scope.
Now, lets change the source for phase B so it's at 90 deg. How many
phases do I have coming out of the box? My answer: two. Change B to
175 deg. How many phases do I have? My answer: two. Change
B to 185 deg, how many phases do I have? My answer: two.
Now change Phase B to 180 deg and how many phases do I have?
My answer: two.
And if I have two there, how exactly is what's coming out of
that box any different than the 3 wires coming into a split-phase
240/120V service? You have a neutral and two phases 180 deg
apart coming out of the box. Between Phase A and neutral you
have 120V. Between
Phase B and neutral you have 120V. Between phase A and Phase B
you have 240V. What's coming out of that box
is identical in every way to what's delivered with a 240/120V
split-phase service. If I hooked either the box or the 240/120V
split-phase service up to your house, there is absolutely
nothing different in terms of current flow, voltage, etc
that is going on at the panel. You could not tell the difference.
Another way of looking at it. I could replace the power source
in the box with a center-tap transformer that delivers 240/120V
split-phase and you could not tell the difference. The electrical
charecteristics on the 3 wires coming out would be EXACTLY the same.
My position is clear. The 180 deg phase relationship is just
one special case of the various possibilities. You can still
view it as two phases, treat it that way from an engineering
analysis basis, etc. The opposing view is apparently that
something magical happens at 180 deg, so that it can no longer
be referred to as 180 deg out of phase, it must only be called
"opposite" or some other imprecise non-engineering term. In fact,
no one who says I'm confused has yet given their definition of "phase",
though I've asked 10 times now. How can you even talk about
something, when no one will define it?

He is proposing that you consider them 2 phases to analyze it.
And says that is a change from how "distribution engineers" view
split-phase.

"Distribution engineers have treated the standard "singlephase"
distribution transformer connection as single phase because from the
primary side of the transformer these connections are single phase and
in the case of standard rural distribution single phase line to ground."
He is suggesting a change from that view.

It is not really clear what he is saying when all we have is a summary
of the paper.
But he says he is proposing a change from how split-phase is viewed by
"distribution engineers".

The currents are not necessarily 180 degrees out of phase even though
the voltages are. That is not something new. I have analyzed currents in
a split phase system without considering the voltages are different
"phases".
The summary does not indicate if he is talking about more than that.

It is a way of referring to the wires. And a way that is consistent
through the piece with 3-phase diagrams.
A single 120V circuit has a "Phase A" wire? What is the point of that?

Also uses "Hot Leg L1 and L2".
Find me a 2 phase panel.
Other opinions here all disagree with you. Some of us are involved in
power distribution.
Your IEEE paper agrees with us.
You can call it whatever you want to. IMHO calling the legs "phases"
adds to confusion.
But I don't really care.

y systems are not single phase line to ground systems, instead they are thr
ee wire systems with two phases and one ground wires. Further, the standard
120/240 secondary is different from the two phase primary system in that t
he secondary phases are separated by 180 degrees instead of three phases se
parated by 120 degrees."

es

s

You can analyze them any way you want. It doesn't change what is there.

What more does he need to talk about:
"Which now brings into focus the reality that standard 120/240 secondary sy
stems are not single phase line to ground systems, instead they are three w
ire systems with two phases and one ground wires. Further, the standard 120
/240 secondary is different from the two phase primary system in that the s
econdary phases are separated by 180 degrees instead of three phases separa
ted by 120 degrees."
It's as clear as can be. He doesn't say, that there really are
not two phases present, but we can pretend there are. He says the
*reality* is there are two phases.

.

And a way that says you have two phases, Phase A and B, and that they
are 180 deg out of phase with each other.

We're not looking at just a single 120V circuit. We're looking at
a 3 wire circuit.

leSplitPhaseandMultiWireBranchCircuits.pdf

Sure. I have no problem with that. But why skip the elephant in the room:
"The primary side of the Distribution Transformer is connected between Grou
nd and one of the 2400V, 7.2 kV, 12.47 kV, 13.2 kV or 13.8 kV
phases of the utility company's 3-Phase Distribution Network. The secondary
of the Distribution Transformer has a grounded center tap and is
wound in a manner that supplies two 120 VAC phases which are 180° out of
phase with each other (Split Phases)
The center-tapped configuration of the secondary side of the Distribution T
ransformer provides following voltages to the Service Entrance Panel:
• 120 VAC between the Hot Leg L1 (Phase A, Red wire) and the grounded, ce
nter tapped Neutral (White wire). The oscilloscope trace of the
voltage waveform between the Hot Leg L1 and Neutral shows the voltage risin
g in the Positive direction at the start of the waveform
• 120 VAC between the Hot Leg L2 (Phase B, Black wire) and the grounded,
center tapped Neutral (White wire). Please note that the
corresponding oscilloscope trace of the voltage waveform between the Hot Le
g L2 and Neutral shows the voltage rising in the Negative
direction at the start of the waveform. This indicates that the two 120 VAC
voltages are 180 degrees out of phase
• 240 VAC between the Hot Leg L1 (Phase A, Red wire) and the Hot Leg L2 (
Phase B, Black wire)"

What something is commonly called doesn't change physics or electrical
engineering. It's like saying because you call something Kleenex,
it isn't actually a piece of soft tissue paper.

That isn't true either. We had one poster describing how
transformers are used to create phases in farm pump applications
that agreed with me. I also believe nightcrawler said he agreed with me.
Some of us are involved in

It agrees only with what it's been *called* by the power
industry and clearly says that while it's called single phase,
in reality you have two phases and that is how you need to
model it. That is what the paper is about.

You must, because you're still posting. And I'm still waiting for
a answer to the simple question of your definition of the term "phase".
Why is it that despite me having asked 12 times now, not one of those
arguing against me can even define it? How can you talk about something
you won't define?
And why no response to my detailed example of going from 3 phase,
to two phases that then looks just like a split-phase service?
Here's another example. People here have brought up
the 100 year old two phase system where the phases were 90 deg
apart. OK, I'll play that game. So we have two phase wires, A
and B and a neutral. Phase B is 90 deg apart from Phase A. Everyone
here seems to agree that two phases are present, right?
So, now let's make phase B 120 deg apart. Still two phase? Let's
make it 280 deg apart. Still two phase? Let's make it 170 deg.
Still two phase? Let's make it 180 deg apart, still two phase?
And if it's suddenly no longer two phase, why not and by what definition
of the term "phase"? And if it is two phase, then it's also electrically
indistinguishable from split-phase 240/120 coming into your house
from the service. That is the reality and that is exactly what the IEEE
author is saying. A phase difference of 180 deg is just one special
case of a phase relationship.

Yes. Indeed. Thank you *all* very much.
I especially loved the gfretwell pictures (they were gorgeous!).
I can't wait to get an ammeter to test my currents at the pole!

I agree. Since I'm *not* an EE, and never will be, I'm *just* a
homeowner, who wants to understand a bit more than I did.
And now, I do. I can recognize now things in my main breakers
that I never noticed before, and, I can recognize similar things
in my three subpanels.
This is all good information!
Thanks.

zero reference. But that technically is not necessary. Your house would
work fine without it. Your oven would still "see" 240 volts and your light
s 120. The problem is you might have a voltage difference between some of
your equipment and ground.

y be tapped at 60, 120, 180 and 240 volts referenced from tap to "low" term
inal.

Tell that to the IEEE power engineers. From the absract of a paper present
ed
at a recent IEEE conference of power engineers:
http://ieeexplore.ieee.org/xpl/articleDetails.jsp?reload=true&arnumber4520128
"Distribution engineers have treated the standard "singlephase" distributio
n transformer connection as single phase because from the primary side of t
he transformer these connections are single phase and in the case of standa
rd rural distribution single phase line to ground. However, with the advent
of detailed circuit modeling we are beginning to see distribution modeling
and analysis being accomplished past the transformer to the secondary. Whi
ch now brings into focus the reality that standard 120/240 secondary system
s are not single phase line to ground systems, instead they are three wire
systems with two phases and one ground wires. Further, the standard 120/240
secondary is different from the two phase primary system in that the secon
dary phases are separated by 180 degrees instead of three phases separated
by 120 degrees."
I'm still waiting for you to explain your definition of the word phase.
Should be easy, as it's a very basic engineering term. If you know what
it is, then why can't you define it?

They are confusing "phase" with "ungrounded conductor"
Two ungrounded conductors that are 180 degrees out of phase are simply
single phase, looked at from different ends.
If you draw a line from the north pole to the south pole, it is still
one line, no matter which end you look at it from.

s a zero reference. But that technically is not necessary. Your house wou
ld work fine without it. Your oven would still "see" 240 volts and your li
ghts 120. The problem is you might have a voltage difference between some
of your equipment and ground.

tion transformer connection as single phase because from the primary side o
f the transformer these connections are single phase and in the case of sta
ndard rural distribution single phase line to ground. However, with the adv
ent of detailed circuit modeling we are beginning to see distribution model
ing and analysis being accomplished past the transformer to the secondary.
Which now brings into focus the reality that standard 120/240 secondary sys
tems are not single phase line to ground systems, instead they are three wi
re systems with two phases and one ground wires. Further, the standard 120/
240 secondary is different from the two phase primary system in that the se
condary phases are separated by 180 degrees instead of three phases separat
ed by 120 degrees."

Two points:
1 - Who is the "they" that are confused? The IEEE engineers at a power eng
ineering conference? The IEEE peer reviewed publication? The author
of so many very technical papers published by the IEEE? The two manufactur
ers
of electrical eqpt with white papers?
2 - Saying "they are confusing phase" isn't a definition of phase.
Why is it that no one that says I'm wrong can give their definition
of a very basic electrical engineering term? Until you can define it,
what's the point? I gave my definition, which I believe is consistent
with it's use in the broadest sense of electrical engineering days ago.

And the north pole still differs by approximately 180 deg from the south po
le.
In essence, someone stating that, with regard to split-phase, ie that the t
wo
legs are 180 deg opposite in phase, is what started all this.

I imagine I could get an argument started at an IEEE meeting about
what you call single phase too but it would not happen at an IAEI
meeting. If you are talking about things in the NEC, the definition is
well established.
You guys rock on. I am out of this

Except of course there is no evidence that there was ever any
argument. The paper was presented by an IEEE engineer with a long
list of technical papers on power systems, power systems modeling,
etc. It was presented at an IEEE conference on power engineering.
It was published by the IEEE.
If you are talking about things in the NEC, the definition is

The definition of what? You've hurled insults, that I'm confused
or know very little. All I've asked of you is to define the
electrical engineering term phase. Yet, you can't do that.

I asked the question about a multiple tap transformer because I don't under
stand the details about how a part of a circuit gets "out of phase."
We're using the word phase in several different ways and that's part of the
confusion at least for me.
I'm not sure it makes sense to say the two lines of a 240 volt service are
180 degrees out of phase even if technically they are, because that seems t
o imply a two phase supply, and that you can create an infinite number of p
hases with a multiple tap transformer.
In my blissful ignorance I just always considered one line to be +120 volts
referenced to ground, and the other -120 volts. I'm pretty sure that's wr
ong, but at least it's not confusing.
I admit I don't understand the fine details here. So, suppose I take my 12
0 volt singlephase house current, and I connect two incandescent light bulb
s in series, each with a resistance of 60 ohms. Total resistance is now 12
0 ohms so I should have 1 ampere of current flowing. If I measure the volt
age across both bulbs I should have 120 volts; but if I measure from betwee
n the two light bulbs in either direction I will read 60 volts (and the bul
bs won't be all that bright). (but I don't care, I'm not going to read by
them; this is a thought experiment)
NOW: are those two voltages 180 degrees out of phase? If not, why not? T
his is exactly analogous to the center tapped transformer, with the sole ex
ception that I didn't ground the center of the lightbulb circuit.
What if I used 4 bulbs? Etc.

erstand the details about how a part of a circuit gets "out of phase."

he confusion at least for me.

e 180 degrees out of phase even if technically they are, because that seems
to imply a two phase supply, and that you can create an infinite number of
phases with a multiple tap transformer.

See the new thread I just started on electrical phases. I laid
out an interesting exercise in looking at phase, where I start out
with what everyone here agrees is 3 phase and morph it into two
phase and it's identical, indistinguishable, from split-phase 240/120V.

ts referenced to ground, and the other -120 volts. I'm pretty sure that's
wrong, but at least it's not confusing.

It's not wrong. But when you have a periodic waveform and one
wave is the inverse of the other, it's also referred to as an 180 deg
phase difference. That one leg is 180 deg out of phase with the other.
And if you look at those two waveforms on a scope, that is what you see.
Here from white papers from electrical eqpt manufacturers:
http://www.samlexamerica.com/support/documents/WhitePaper-120240VACSingleSp
litPhaseandMultiWireBranchCircuits.pdf
http://www.behlman.com/applications/AC%20basics.pdf

120 volt singlephase house current, and I connect two incandescent light bu
lbs in series, each with a resistance of 60 ohms. Total resistance is now
120 ohms so I should have 1 ampere of current flowing. If I measure the vo
ltage across both bulbs I should have 120 volts; but if I measure from betw
een the two light bulbs in either direction I will read 60 volts (and the b
ulbs won't be all that bright). (but I don't care, I'm not going to read b
y them; this is a thought experiment)

If you look at the ends of the two bulbs referenced to the mid-point,
then yes. When one is +60, the other will be -60. You could hook up
a scope, use the center as the reference, put one probe on the top of
one bulb, the other on the bottom of the other bulb and you'd see two sine
waves, 180 deg out of phase. The disagreement is that those on the other
side of this refuse to call that a phase difference. They say it's just
180 deg opposite. Well, when you have two sine waves that are the opposite
of each other, their phase relationship is that they are 180 deg apart.
Which is why I've asked those on the other side 10 times to simply define
the term phase. Yet despite telling me that I'm the one that is
confused, not one of them can define it. How can you speak about
something and not be able to define it?
This is exactly analogous to the center tapped transformer, with the sole
exception that I didn't ground the center of the lightbulb circuit.

If you use 4 bulbs in series and used the center point as a reference,
you would see +30V, +60V, -30V, -60V again with the sine waves 180 deg
out of phase.

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